How can I make collision detection between obstacles (box) and car? ):

Also

How do I put text on my screen, on the top right I want to put "score" + points - this would be a float or integer variable I guess but I just can;t seem to find the code to display text and numbers.... why do they make things so complicated

You need to have Frustum first, and for that something called AABB. These are cubes(AABB)/spheres for defining your Frustum.
If you have all parameters you don't need to calculate Frustum parameters, just calculate distances with hand/calculator
To detect culling, calculate were boxes you defined intersect, the region of intersection with current radius, is your occlusion culling plane.